Blender Fund is using its own authentification system (Blender ID) using OAuth2. There was also quite a bit of work with the layouts of the page since Krita main CSS theme is using Bootstrap 3 and the Blender Fund website is using Bootstrap 4 and were was many subtle differences between both versions. Updating only the templates made it possible to customize the website’s look and edit the content of the emails sends by the system to use Krita billing information instead of Blender one.